Time-resolved photoluminescence (TRPL) is a powerful tool to characterize the carrier dynamics in semiconductors. In many situations such as in solar cells and photodetectors, the excess carrier decay behavior at low excess carrier densities give more valuable information since it is close to device working condition. However, the photoluminescence (PL) signal is weak from samples with low excess carrier density, and specifically for the infrared regime, the background blackbody radiation contributes significantly to the overall noise. While approaches such as improving the light collecting efficiency or increasing the detector effective area can increase the collected signal intensity, the former needs complicated optical system design and the latter sacrifices the system band width due to larger parasitic capacitance. A long integration time is therefore required to suppress the noise and achieve a proper signal-to-noise ratio for TRPL measurements.
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